Exhaust machine and method of protecting exhaust systems



D. MULLAN 2,254,905 METHOD OF PROTECTING EXHAUST SYSTEMS Sept. 2, 1941.

EXHAUST MACHINE AND 3 Sheets-Sheet. 1

(maul/mm ATTORNEY D. MULLAN Filed Nov. 25, 1938 3 Sheets-Sheet 2- INVENTOR flfl/V/AZ MVZZ/I/Y. BY

dug n! m m ATTORNEY v Q I I LHHIHHIIIHII I Sept. 2, 1941.

EXHAUST MACHINE AND METHOD OF PROTECTING EXHAUST SYSTEMS p 2, 9 1. D. MULLAN 2,254,905

EXHAUST MACHINE AND METHOD OF PROTECTING EXHAUST SYSTEMS Filed Nov. 25,' 1938 3 Sheets-Sheet 3 Patented Septr 2, 1941 UNITED STATES PATENT OFFICE ExuAUs'f MACHINE AND METHOD or PRO- TECTING EXHAUST SYSTEMS Daniel Mullan, Kearny, N. -J.,' assign0r to Westinghouse Electric 8; Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania,

Application November 25, 1938, Serial No. 242,196

' 24 Claims.

This invention relates to machines for gas filling and/or exhausting hollow bodies, and particularly to such used for the manufacture of incandescent electric lamps and similar devices.

In exhaust equipment of the type contemplated '5 and particularly adapted for the evacuation ofg incandescent electric lamp bulbs, there is in each head assembly a port closing mechanism, usually comprising a rubber tube and pinch clamp, and

a compression rubber release mechanism. The 1 purpose of the first named, is to close the exhaust port against atmospheric pressure in the event of a broken lamp or leaker, or an open exhaust port passing a given position. The purpose of the second named, is to hold the exhaust tube of each lamp securely in an air-tight connection by compression of an exhaust rubber.

Heretofore, the development of a leaker or the breaking of a lamp bulb, would result in affecting the exhaust to that extent and depleting the vacuum by the admission of atmospheric air.

In accordance with my invention, I have provided means for closing the port and releasing the compression rubber to permit the removal of the defective lamp, or other device being evacu- 25 ated, by a single movement of a lever electrically operated by means of a solenoid.

It is, therefore, one of the p incipal objects of I, my invention to automatically guard against contamination, or impairment of the exhaust system, by the development of leaks due to such causes as broken or leaky lamps, at a predeter-' mined position in the exhaust schedule.

Another object of my invention is the employment of a Pirani gauge, calibrated to operate at a predetermined pressure through a relay and solenoid, in order to close the pinch clamp and cut off the exhaust equipment from the atmos,

phere, as well as release the pressure on the rub- 40 ber receiving the exhaust tube of the defective lamp or device being evacuated. and thereby conserve the vacuum by preventing contamination and depletion by the admission of atmospheric air, as well as facilitate removal of the defective lamp or other device being evacuated.

A further objector my invention is to improve lamp quality through automatic protection of the exhaust system, and relieve the operator from the necessity of observing a signal lamp or other similar means for detecting poor vacuum or broken lamps on an exhaust machine.

A still further object of my invention is the automatic closing of the connection between an exhaust head and the vacuum pump, and the Ice lieving of the compression on the rubber with which the exhaust tube of a device being evacuated connects, by a single movement of a lever operated by a solenoid automatically controlled by a Pirani gauge or other vacuum measuring device. 7

Other objects and advantages of the invention, relating to the particular arrangement and construction of the various parts, will become apparent as the description proceeds.

Referring to the drawings illustrating my in- A vention Figure l is a fragmentary plan of an exhaust machine embodying my invention. I Figure 2 is a fragmentary elevational view of the machine on the line II-,II of Figure l, in

the direction of the arrows, but showing a slight I modification.

Figure 3 is a fragmentary vertical sectional view on the line III-HI of Figure l, in thedirection of the arrows, butalso showing a valve in the insert gas line.

Figure 4 is'a fragmentary view, Icorresponding to Figure 3, but omitting the inert gas line valve connection between the head and the vacuum valve upon the development ofa leak.

The present invention may be embodied in any suitable type of exhaust machine, such as used for the progressive evacuation of hollow bodies,

and particularly in connection with vacuum or gas-filled electrical devices, such as incandescent lamps,'radlo tubes and the like.

Exhaust machines for the above mentioned purpose are usually provided with two pumps,,a preliminary exhaust p p diagrammatically illustrated and designat din Figure 5 by the reference, character I l, and a. final exhaust pump diagrammatically illustrated and designated by the reference character l2. evacuated, here shown as incandescent electric lamp bulbs and designated by the reference character l3,

The devices to be i are first connected with the preliminary pump II, and exhausted as they travel with the conveyor [4, while mounted on heads I5, that is, they are moved from one station to another while being exhausted. The same procedure is followed when the devices are subjected to the second or final exhaust pump l2.

In an exhaust machine, such as described and claimed in my Patent No. 2,113,798, dated April 12, 1938, and owned by the assignee of the present application, each conduit from the vacuum pumps to the devices being evacuated, is provided with a plurality of ports l6, arranged to communicate with a plurality of slots I1, disposed in two circular rows and staggered with respect to one, another. The conveyor l4 moves with the upper valve section l6, and communication is had with the pumps through the ports IS in said upper valve section, which successively communicate first with the slots I1 connected to the preliminary pump H, and then those which connect with the final pump l2, so that a progressive evacuation of the lamp bulbs or other devices, is effected during movement of said devices from the initial position at station number I, as shown in Figure 5, to station number I6, where each is removed from the exhaust apparatus.

In view of the fact that the gradual exhaust of lamp bulbs and the like, as well as the admission of flushing and filling gas is known to those skilled in the art, and a machine for which the present invention is especially adapted, has been described in my patent, previously referred to, I will not further describe the exhausting operation, simply stating that my invention in-v volves an improvement on the machine of the patent mentioned, especially when said, machine is equipped with the type of heads, such as 11- lustrated in Figures 3 and 4.

The machine now being described, is desirably provided with a series of bulb holders, not fully shown, usually termed heads and here designatedby the reference character I5. Each bulb holder I includes an exhaust port 2|. The heads on the machine are of similar construction and, inasmuch as the structure is generally well known in the art and more fully shown in the Mullan patent previously referred to, only the /'exhaust port 2| and portions associated therewith, are illustrated.

As the heads move with the conveyor I4, the supported lamps or other hollow bodies l3 are progressively connected, first to the vacuum pump H, and then to the vacuum pump l2, as through line 22, by means of the valve comprising the top section l8 and the bottom section 23. These valve sections are in the form of rings having flat opposed surfaces 24 and 25, with an interposed oil seal fed through passage 26. The top valve section I8 is moved as by a drive shaft, not shown, with the conveyor plate I4 being connected thereto, in any desired manner. Pressure springs, not'shown, may serve to hold the upper section in close relation with the lower section 23, which is held stationary as by dowel pins, not shown, extending from said valve section into the frame 21.

The valve sections l6 and 23, which constitute a valve unit, serve to open and close the vacuum lines l6, as well as the inert gas supply lines 23, 28 and 3!, if the latter are used, to the bulbs l3 supported in the heads [5. In making gas-filled lamps, each lamp may be first exhausted and then filled with a gas, again exhausted, and finally filled with an inert gas, such as argon, the gas-filling pipe being, in the present embodiment, designated by the reference character 32.

Each head is desirably provided with an apertured exhaust rubber or conduit 33 in the portion provided with the exhaust port 2|. This exhaust rubber is mounted in a fitting 34, to which is threaded a cap 35 provided with a laterally extending arm 36, and adapted to be cam-actuated to either press a washer member 31 through ball bearings 33 against the exhaust rubber 33 to squeeze it about the exhaust tube 39 of the lamp II at the proper time, to effect an air-tight con nection therewith, or release the pressure thereon to facilitate insertion or withdrawal therefrom. The exhaust rubber connection just described, may be, generally, as shown in the Gustin Patent No. 2,215,100, dated September 17, 1940.

Air is exhausted from the lamp l3 through the exhaust pipe 22, trap 4|, and rubber tube connection 42, mounted in the head and adapted to be closed as by means of a pinch clamp 43, forming a valve which may be operated through its arm 43 as desired, or automatically upon the development of a leak, as will subsequently be explained.

Connection with the vacuum pumps II and I2 and their manifolds 44 and 45, is effected through lower valve section 23 and vacuum lines l6, by means of rubber hose connection 40; a similar connection providing for the introduction of inert gas, it employed.

In order to effect the actuation of the pinch clamp 43 to close off the vacuum line 22 from the atmosphere in case the bulb l3 leaks or is broken, as well as releasing the exhaust rubber- 33 to permit removal of the bulb [3 and/or exhaust tube 39, I provide a vacuum sensitive device, such as a Pirani tube 46, connected to the lower valve section 23, as by means of a pipe 41, and'rubber hose 48. This connection is desirably made at what is termed position or station number l2 on the exhaust machine, that is, near the beginning 01' the final exhaust. The possibility that the exhaust tube of a lamp may not be inserted in every exhaust rubber 33, is desirably taken care of earlier in the exhausting process by automatically closing the pinch clamp 43 of the vacant head at position 4. The purpose of making the Pirani tube connection at this particular point, is to avoid spoiling the final vacuum and ruining lamps, or other devices being evacuated, adjacent the defective device being exhausted, and catch leakers which may not show up until the exhaust-is nearly complete.

A Pirani tube comprises a platinum filament 49 in an envelope 5|, the resistanceof said filament being dependent on its temperature which, in turn, depends on the nature and pressure of the gas surrounding it, so that if a given voltage is applied to said filament, its resistance will vary upon a change of the vacuum from normal. By suitable calibration such a tube may serve, upon depletion of the vacuum to a predetermined extent, to upset the balance of a Wheatstone' bridge, designated by the reference character 52, to thereby energize a relay magnet 53, to draw its armature 54, to close a circuit, to be subsequently described, and effect the desired operations.

In the present embodiment, the Pirani tube 46 is shown connected across one side of the Wheatstone bridge 52, balanced against resistances 55, 56 and 51, each desirably of ohms, and closing the other three sides of the Wheatstone bridge 52. Energization of the bridge is effected by connection with the secondary winding 66 of a transformer 59, through a rectifying unit 8|, so that ten volts direct current are, in the present embodiment, applied to two opposite corners of the bridge 52.

The relay magnet 53 in the present embodiment, is indicated as having a resistance of 120 ohms and the winding is such that when the balance of the bridge is upset by the vacuum deteriorating from a normal of less than 25 to 35 microns, to as high as 80 microns, suflicient current passes through the relay to draw the armature 54 to close the circuit 62, supplied from the secondary winding 58. to thereby energize signal lamp 63 and solenoid 64. V

The solenoid 64, when energized, raises its armature 85, and mo' es the connected lever 68 from the position shown in full to that shown in dotted lines in Figure 2 about the pivot 61 in standard 68, connected to the bracket 69 mounted on the frame 21 of the machine. The movement of the lever 66 reciprocates the rod H upwardly in its bearing 12, supported in housing I3, also mounted on bracket 69, against the pressure of the coil spring 14, acting between the bracket 69 and the collar I5, secured to the rod H as by means of set screw 16. The rod is desirably prevented from dropping below its normal inoperative position by means of a collar 11, secured thereto by set screw 18, and normally engaging the upper end of housing 13.

The rod II carries, adjacent its upper end, a cam roller 19 adapted to form an obstruction and operatively engage the arm 36 when raised to the dotted position shown in Figure 3, and a cam roller 8|, adapted to form an obstruction and operatively engage the pinch clamp 43 when raised to the dotted position represented in Figure 3, as the conveyor moves to carry the heads from station to station. The roller BI, is pivoted on a reduced section 82 of the rod H, between a shoulder 83 and the roller 19. The roller 19, is pivotally mounted on a screw 84, threaded to the reduced section 82, as indicated at 85, and disposed between the head 86 of said screw, and the reduced section 82 on the rod H.

The operation of the apparatus, described in accordance with my invention, will occur if and when a bulb l3 reaches position number l2 on the exhaust machine, and said bulb is either leaking to the extent that the vacuum at that position breaks to a degree, in accordance with the calibration of the Pirani tube 46, which, in the preferred embodiment described, is 80 microns, or the lamp is broken. I

Immediately, when one of these events occurs, the normally balanced'Wheatstone bridge 52 becomes unbalanced by a decrease in the resistance of the filament 49, resulting in a flow of current between the corners 81 and 88 of the Wheatstone bridge 52, through the relay magnet 53,

moving the armature 54 from right to left, as

viewed in Figure 5, energizing the signal lamp 63, and closing the circuit through the solenoid 64 to raise the lever 66 and the connected cam 'rollers 19 and 8|, from the full to the dotted line positions shown in Figures 2 and 3, so that they stand in the path of the arm 36 and pinch clamp 43 of the adjacent head l5, to thereby cause the vacuum line 22 to be disconnected from the atmosphere, and the exhaust tube 39 released, to allow removal of the defective or broken lamp l3, and/or its exhaust tube, or other action to overcome the depleting effect on the vacuum, thereby preventing the further manufacture of defective lamps or such insufficiently exhausted.

If it is desired to also conserve the inert 1111 gas, if lamps of the gas-filled type are being made, the inert gas line 32 may be controlled by a suitable valve therein, comprising, for example, a pinch clamp 3|, operated by a suitable cam 92, so connected to the arm 36 that when the exhaust rubber 33 is released, the rubber tube connection 93 in the line 32 is closed, thereby preventing further flow of Such a valve, like the valve 42-43, may be made to operate simultaneously with movement of the pinch clamp 43, and/or movement of the arm 36, if desired, as will be understood.

As afurther alternative, the fill or inert gas line 32 may connect directly with the exhaust line 22, as indicated by dotted lines in Figure 2, and designated by the reference character 83, so

that the inert gas supply is simultaneously cut off upon closing the tube 42. i

From the foregoing disclosure, it will be seen that I have provided means for closing the exhaust port, as well as the inert gas inlet if gas- 'filled devices are being made, and releasing the compression rubber, by a single movement of a preferably released on the compression rubber,

making it possible for the exhaust tipping torch holder to remove the defective lamp with the exhaust tube at one time.

In normal operation, and in case a leaker reaches position number l2, for example, on the machine, the, roller cams 19 and 8| are raised to position to function during movement of the head, from position |2 to position l3. By the use of my invention, an improvement in lamp quality is effected through protection of the exhaust system, and the operator is relieved of the necessity of observing a signal lamp for detecting poor vacuum or defective or broken lamps on the exhaust machine.

Although preferred embodiments of my invention have been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims.

I claim:

1. The method of protecting an exhaust system against contamination due to leaks, comprising automatically energizing an electric circult to close the connect on through which a leak would take effect and release any associated leaking device for disconnection from said exhaust system, upon an increase in pressure in saidtexhaust system beyond a predetermined poin 2. The method of protecting an exhaust system against contamination due to leaks. comprising automatically operating a Pirani tube upon an increase in pressure insaid exhaust system beyond a predetermined point. to close the exhaust port and release the compression rubber conduit 01 the system of a leak. by a single movement of a lever operable by a solenoid in circuit 'with a relaycontrolled by said tube.

. 3. Anexhaustirnachine comprising, a head in-.

fill gas 1 therefrom. 3

uponthe development exhaust tube of a device being evacuated, and an arm adapted upon rotation thereof to effect compression of said conduit to grip said exhaust tube therein, and means to automatically move said arm for releasing the exhaust tube of said device for disconnection from the machine, upon an increase in pressure in said machine beyond a predetermined point.

4. An exhaust machine comprising a rotary conveyor, an exhaust head mounted on said conveyor and including a rubber conduit adapted to receive the exhaust tube of a device being evacuated, and an arm adapted upon rotation to effect compression of said conduit to grip an exhaust tube fitted therein, and means facilitating the removal of leaky devices for protecting the exhaust system in said machine against contamination, comprising an electric circuit energized automatically upon an increase in pressure in said system beyond apredetermined point, to close the connection to said head, and move back said rotatable arm to release any associated leaking device for disconnection from said machine.

5. An exhaust machine comprising a rotary conveyor, a plurality of exhaust heads mounted on said conveyor and each including a rubber conduit adapted to receive the exhaust tube of a device being evacuated and an arm adapted upon rotation to effect compression of said rubber conduit to grip such an exhaust tube fitted therein, and means facilitating the removal of leaky devices for protecting the exhaust system in said machine against contamination due to leaks, comprising an electric circuit energized automatically upon an increase in pressure in said I compression of said -rubber conduit to grip such an exhaust tube fitted therein, and means operable automatically uponan increase in pressure in said machine beyond a predetermined point, and controlled by a Pirani tube, to move a lever and close the connection to the head with which a leaking lamp bulb is associated, and release the compression in said rubber conduit.

7. An exhaust machine for lamp bulbs comprising a rotary conveyor, a plurality. of exhaust heads mounted on said conveyor and each including a rubber conduit adapted to receive the exhaust tube of a lamp bulb and an arm adapted upon rotation to effect compression of said rubber conduit to grip such an exhaust tube fitted therein, a valve unit including an upper rotary disc valve'section and a lower stationary disc valve section, said sections having fiat surfaces in contacting relation and ports lying along said surfaces for eflecting transfer of gases therebetween, vacuum lines between the upper valve section and each head. and means for protecting the exhaust system in said machine against contamination due to leaks, comprising an electric cluding a rubber conduit adapted to receive the haust tube of any associated leaking device for disconnection from said machine.

8. An exhaust machin for lamp bulbs comprising a rotary conveyor, a plurality of exhaust heads mounted on said conveyor and each including a rubber conduit adapted to receive the exhaust tube of a lamp bulb and an arm adapted upon rotation to'efiect compression of said rubber conduit to seal such an exhaust tube fitted therein, vacuum lines including a rubber tube sion of the rubber conduit to allow for disconnection of a leaking bulb, it connected to said head, for removal from said machine.

: 9. An exhaust machine for lamp bulbs, com- ,prising a rotary conveyor, a plurality of exhaust 'heads mounted on said conveyor and each including a rubber conduit adapted to receive the exhaust tube of a lamp bulb and an arm adapted upon rotation to effect compression of said rubber conduit to seal such an exhaust tube fitted therein, and means' for protecting the exhaust system in said machine against contamination due to leaks, comprising a Pirani tube so connected that it measures the vacuum in each head as it reaches a predetermined station adjacent the beginning of the final exhaust, an electric circuit between the filament of said tube and one side of a Wheatstone bridge, balanced for normal operation, a relay magnet connected across said bridge, and adapted to operate its armature to close a circuit through a solenoid when the pressure in the Pirani tube increases to a predetermined extent above the normal vacuum, in order to effect closure oi! the connection to the head responsible for a leak and movement of the compression arm to release any associated leaking device for disconnection from said machine.

10. An exhaust machine for lamp bulbs comhaust tube fitted therein, and a pinch clamp adapted to close the exhaust connection to said head, and means for protecting the exhaust system in said machine against contamination due to leaks and facilitate the removal 01' leaky devices, comprising an electric circuit energized automatically upon an increase in pressure in said exhaust system beyond a predetermined point, to actuate the armature of a solenoid and move a lever to transport cam means into position to be engaged by the compression arm and pinch clamp of each head, in order to successively close each exhaust port against atmospheric pressure and release any associated exhaust tube from its rubber conduit.

11. An exhaust machine for lamp bulbs comprising a rotary conveyor, a plurality of exhaust heads mounted on said conveyor and each including a rubber conduit adapted to receive the exhaust tube of a lamp bulb, and an arm adapted upon rotation to effect compression of said rubber conduit to seal such an exhaust tube fitted therein, a valve unit including an upper rotary disc valve section and a lower stationary disc valve section, said sections having fiat surfaces in contacting relation and ports lying along said surfaces for efiecting transfer of gases therebetween, means for moving said upper section with said conveyor, vacuum lines including a rubber tube connection between each head, and the upper valve section, a pinch clamp associated with each rubber tube connection and adapted to be moved to closed or opened position, preliminary and final vacuum pumps, means connecting said pumps to said lower valve section so that, as the upper section and conveyor move, bulbs in said heads are progressively exhausted, a Pirani tube connected to said lower valve section at a station adjacent the beginning of the final exhaust, an electric circuit between the filament of said tube and one side of a Wheatstone bridge balanced for normal operation, a relay magnet connected across said bridg and adapted to operate its armature to close a circuit through a solenoid, when the pressure in the Pirani tube increases to a predetermined extent above the normal vacuum, a lever operable by said solenoid, and cam means'movable by said lever upon operation of said solenoid to be engaged by said compression arm and pinch clamp, in order to effect closure of the exhaust 7 port against atmospheric pressure and release of the exhaust tube from its rubber conduit.

12. An exhaust and gas filling machine, comprising an exhaust head including a rubber conduit adapted to receive the exhaust tube of a device to be evacuated, exhaust and gas filling connections to said head, an arm to effect opening and closing of said connections, and means operable automatically upon an increase in pressure in said exhaust connection beyond a predetermined point, to move said arm for closing the exhaust and gas filling connections to said head.

13. The method of facilitating the removal I of a leaky or broken hollow device being evacuated and having an exhaust tube clamped in an exhaust rubber conduit by pressure on said conduit, comprisingautomatically closing the connection to and releasing the pressure on said conduit to free. the exhaust tube of said device for disconnection from, the exhaust system, upon an increase in pressure in said system beyond apredetermined point.

14. The method of facilitating the removal of a leaky or broken device being evacuated and having an exhaust tube received in an exhaust rubber conduit and gripped by pressure thereon applied to said conduit, comprising automatically energizing an electric circuit to close the exhaust connection to and release the pressure on the exhaust tube of said device, upon an increase in pressure in the exhaust system beyond a predetermined point.

15. An exhaust machine comprising a head with an exhaust connection, including a rubber conduit adapted to receive the exhaust tube of a device being evacuated,"an arm adapted upon rotation thereof to eifect compression of said conduit to grip said exhaust tube therein, a valve in said exhaust connection, another operating arm extending therefrom, and means to automatically move both of said arms for releasing valve, upon an increase in pressure in said machine beyond a predetermined point.

16. An exhaust machine for lamp bulbs comprising a head, including a rubber conduit adapted to receive the exhaust tube of a lamp bulb to be evacuated, a valve unit including an upper rotary disk valve section and a lower stationary disk valve section, said sections having surfaces in contacting relation and ports lying along said surfaces for effecting a controlled transfer of gases therebetween, vacuum lines including a rubber tube connection between said head and the upper valve section, a pinch clamp associated with said connection and adapted to be moved to closed or opened position, preliminary and final vacuum pumps, means connecting said pumps to said lower valve section so that, as the upper section moves, a bulb in said head is progressively exhausted, a Pirani tube the bulb of which is connected to said lower valve section at a station adjacent the beginning of the final exhaust, the filament of said tube being in the circuit at one side of a Wheatstone bridge balanced for normal operation, a relay magnet connected across said bridge and adapted to 0perate its armature to close the circuit through a solenoid when the pressure in the exhaust system and Pirani tube bulb increases to a predetermined extent above the normal vacuum, a lever operable by said solenoid, and cam means movable by said lever upon operation of said solenoid to be engaged by said pinch clamp, in

v order to effect closure of the latter.

the exhaust tube of said device and closing said 17. An exhaust machine for lamp bulbs comprising an exhaust head including a rubber conduit adapted to receive an exhaust tube of a device being evacuated, a pinch clamp adapted to close the exhaust connection to said head, and means for protecting the exhaust system in said machine against contamination due to leaks, comprising an electric circuit energized automatically upon an increase in pressure in said exhaust system beyond a predetermined point to actuate the armature of a solenoid and reciprocate a rod to raise cam means into position to be engaged by the pinch clamp of said head, in order to close the latter.

18. The method of protecting an exhaust system against contamination due to leaks, comprising automatically closing the connection through which a leak would take effect, by energizing an electric circuit upon an increase in pressure in said exhaust system beyond a predetermined point, to cause a rod to reciprocate and carry roller means into position to actuate a valve controlling said connection upon normal movement of said valve toward said roller means.

19. The method of conserving filling gas and 20. An exhaust machine comprising a con-.

veyo'r carrying an exhaust head including a tubber tube for receiving the exhaust tube of a device to be evacuated, a valve in the exhaust connection" to said head and having an operating arm extending therefrom, a rod, and a roller supported on said rod, said rod being operable automatically upon. an increase in pressure in said exhaust connection beyond a predetermined point, to raise said roller into the path of said arm for closing the valve as the conveyor moves.

21. An exhaust machine comprising a rotary conveyor, an exhaust head mounted on said conveyor and including a rubber conduit adapted to receive an exhaust tube of a device to be evacuated, a valve in the vacuum oonnectionto said conduit, an operating arm extending from said valve, and means for protecting the exhaust system in said machine against contamination due to leaks, comprising a rod, a roller supported on said rod, and an electric circuit energized automatically upon an increase in pressure in the exhaust system beyond a predetermined point, to reciprocate said rod and move said roller into the path of said arm for closing said vacuum connection as the conveyor moves.

22. The method 01 facilitating the removal of a leaky or broken hollow device being evacuated and having an exhaust tube clamped in an exhaust rubber conduit of an exhaust system by pressure on said conduit, comprising automatically releasing the pressure on said conduit for disconnection of said tube from the exhaust system, upon an increase in pressure in said system beyond a predetermined point.

23. The method of protecting an exhaust system against contamination due to leaks, comprising automatically moving a roller upward into the'path of movement of the operating arm. of a movable shut-ofi valve operating arm controlling the connection through which a leak would take eiiect, to allow it to be engaged by said arm, upon movement thereof, and close said valve upon an increase in pressure in said exhaust system beyond a predetermined point.

24. The method of facilitating the removal of a leaky or broken hollow device having an exhaust tube clamped in an exhaust rubber conduit of an exhaust system by pressure on said conduit, comprising automatically energizing an electric circuit to release the conduit pressure for disconnection-oi the exhaust tube of any such device being evacuated, upon an increase in pressure in the exhaust system beyond a predetermined point.

DANIEL MULLAN. 

